However, sometimes you need to access to some parts of the URL (such as the
database name or the port number) to define the value of other options. In
Symfony 4.3, we've added two new env var processors (url and
query_string) to do that.

The url processor parses the given URL and returns an associative array with
its components, so you can combine it with the key processor:

The query_string processor parses the query string part of the given URL and
returns an associative array with its components, so you can also combine it
with the key processor. If the env var is defined like this:

The new DSN-like configuration surprised me, because it's easier to concatenate strings than the other way around.

A method to undo the concatenation if great, but it feels like a dirty workaround for a problem that doesn't have to (and even didn't?) exist in the first place. What's wrong with setting username/password as environment variables?

@Stephan: It is more practical to use one env variable to configure database access than using many variables and adding more when additional parameter (encoding, protocol version,...) is required. I don't like it in config files, but it makes sense in env variables. This change looks like it brings better of both.